Chevrolet: theft system, o2 sensor, car right

Question
I took my car to the shop and had a new O2 sensor put in.  When they were done the car wouldn't start.  When you crank the car it cranks and runs for a few seconds and cuts off. They seem to think its the fuel pump, but they're not sure. what do you think?

Answer
Travis ;
 Hi - well if its at the station why dont they put the computer on it and see what codes come up. did they put the right sensor in , and is it all hooked up right. I would check that first , even put the old 02 sensor back to see if it will run . I would not start to put new parts on it , you want to find whats wrong not rebuild the car - right..